How many times have you heard people justify their use of plastic with the phrase ‘It’s ok. It’s biodegradable’? We have heard that a lot, especially in supermarkets and in regards to plastic bags. The reality though is that in the majority of people’s minds, the word biodegradable translates to ‘compostable’ or to somethings that, like a leaf, will break down quickly leaving no trace. Unfortunately this isn’t the case. Let’s analyze the true meaning of these different words when associated to various plastic bag options. 

Compostable 

Something is said to be ‘compostable’ when it is capable of disintegrating into all-natural elements without leaving behind any dangerous chemicals or small pieces of plastic. Composting can take place both in a home setting, such as a garden compost, or an industrial compost site.

Things such as leaves or food scraps can take months to be eaten by micro-organisms, fully decompose and turn into safe and natural nutrients which can then be reused for gardening.

The American Society for Testing and Materials (now known as ASTM International) specifies that for a product to be labeled as commercially compostable it must meet specific guidelines, such as:

• It must be able to be broken down by biological treatment at a commercial or industrial composting facility

• Decomposition of the plastic must occur at a rate similar to the other elements of the material being composted (within 6 months)

• It must leave no toxic residue that would adversely impact the ability of the finished compost to support plant growth”

To be able to fully compost without leaving toxic residue in the soil, items need a certain amount of time as well as certain starting conditions such as the correct temperature, the right amount of oxygen and moisture within the heap. This is why if something is marked ‘Compostable’ it is not ok to throw it in your black bin. A lot of people picture landfills as open air compost heaps, but this is not the case. Landfills do not have the right conditions (warmth, air, moisture) to allow items to properly and quickly decompose.

Do your research and find out how to get your compostable items to the industrial waste systems closer to you, or, in alternative, find out how to make your own compost at home. 

Biodegradable 

A bit like the term ‘Compostable’, biodegradable also refers to materials (in this case both solids and liquids) that naturally break down without any special scientific treatment and then naturally re-enter the environment. The difference with compostable materials, is that in this scenario, the process will take a bit longer. If things like leaves, food waste, wood, paper or grass normally take between months or years (depending on temperature and moisture), biodegradable plastic might take between 100 to even 1,000 years to decompose. Yes, it will eventually break down and disappear, but think of how much damage a plastic bag can do to the environment (to wildlife and marine life especially) in 100 to 1,000 years! This happens because even though biodegradable plastic bags are made from plant-based materials such as corn and wheat starch, they still need specific conditions, such as high temperature and UV light, to break down.

Exactly like compostable plastic though, biodegradable plastic bags also cannot be sent to landfill, as they too won’t find the conditions needed to decompose. Landfills in fact are anaerobic environments, meaning that unlike a garden compost heap, they lack air/oxygen, making it more difficult for plastics to break down, and facilitating their production of greenhouse gas, methane. 

Recyclable 

Through recycling a lot of people feel that they are actively making a difference and helping the planet by dividing household waste into the correct bin and ultimately giving it a new life, or choosing items that have already been recycled.

What a lot of people ignore though, is that in some cases, recycling isn’t the ultimate solution, but in truth, it’s just and intermediary step in delaying the inevitable. What we mean by this is that although certain materials, such as for example steel, truly have a closed recyclable loop, other materials such as plastic, have a limited recyclable life-span. Certain plastics in fact may only be recycled seven to nine times, while others can only be recycled once, before they make their way to landfill. This happens because through the process of recycling products and/or materials are actually down-cycled, broken down and turned into a lower-value product.

To find out more about the recyclability of a specific product, take a look at the chasing arrows that symbolize that the product is recyclable, and look for the numbers placed inside the symbol . The numbers go from one to seven and represent the different type of plastic and material that that object is made of. Most of the time plastics that are numbered one and two are recyclable, but plastics that are numbered three through seven include PVC, polystyrene and mixed plastics, meaning that they are harder to recycle.

Which one to choose

The best choice out of these three types of plastic bags would be none of them! Shop package free, avoid and refuse unnecessary plastics and invest in reusable bags, containers or in alternative and sustainable materials.

Everyone needs to understand that there truly is no “away” and that before purchasing anything, we need to look at the bigger picture and fully understand the lifecycle that that particular product/item/packaging will have once we no longer have a need for it, or once it wears out. 

If you really have to make a choice between compostable, biodegradable or recyclable plastic, then of course choose compostable items and either create your very own compost heap, or research an industrial compost site nearby.